1. Field in the Invention
The present invention relates to stator windings for use in rotating electrical devices and more particularly, to an improved method for forming the stator, particular to a roll forming process to efficiently and effectively form the stator.
2. Discussion of Relevant Art
During the manufacture of rotating electrical devices, lengths of wire, called xe2x80x9cconductorsxe2x80x9d, are wound around the stator structure. This winding process usually causes the windings and internal motor leads to be formed through relatively narrow apertures and into wire slots, which can often cause the insulation on the conductors to be damaged. When a rotating electrical device is used in a high temperature and/or in a corrosive environment, the damage caused on the insulation can cause premature failure of the device.
This invention is particularly suited to a stator having splines formed about an outer or inner periphery of the central stator body. For this design, the windings must be threaded between the splines through a narrow gap between each successive spline during the manufacturing process. That operation can cause damage to the windings and lack or wire fill in the slots.
There is a need for improved stator structure and a method of making same which will reduce the manufacturing costs, help wire slot fill, and reduce the likelihood of damage to the insulation of the conductors, and thus eliminate or minimize the risk of resulting failure and improve stator output.
The present invention has been contemplated to overcome the foregoing deficiencies and to meet the above-described needs. Specifically, the present invention comprises a stator structure for a rotating electrical device with stator windings formed by conductors coated with insulation. During the manufacture of the stator structure, specifically the stator splines, are formed to improve the manufacturing process and allow more fill, which reduces imperfections and damage to the windings and produces more output.
The device and method of this invention is used to perform a flaring operation on a cylindrical automotive alternator component (stator) designed with a number of evenly spaced axially oriented splined around its inner or outer diameter. The design of the stator requires that these perimeter splines possess a flared end to retain the windings, creating a rounded cavity contour between the adjacent splines. The splines would be put into the cylindrical surface of the stator by means of another process, e.g., a wire EDM process, stamping or cold forming, prior to the winding operation.
To form the flared outer or inner portion according to the invention, the preferred embodiment of the invention uses a series of forming rollers that pass lengthwise along each spline to gradually and sequentially flare out the end surface of the spline. Each roller deforms the material slightly, spreading the material in the circumferential direction, and the successive rollers are designed to make an additional incremental deformation to the same surface so that after passing a number of rollers across the spline the flared geometry is achieved.
Preferably, these rollers are contained within a large carriage, designed to carry the rollers at the correct spacing relative to each other and relative to the component being worked on. Each roller is mounted on suitable bearings to allow it to rotate while being driven against the rotor component. The carriage itself moves in a direction parallel to the axis of the component part, mounted in turn through suitable bearings onto a rigid stationary platform, and powered by a suitable linear motive device such as a hydraulic cylinder.
The stator component to be formed is clamped in place by a supporting clamping mandrel, which supports the stator material against the force of deformation, and also serves to align the splines relative to the position of the rollers. This same clamping mandrel may be indexed rotationally to present successive splines to the same forming action, or the rollers may be formed to contact more than one spline at a time. The result is that with a single stroke of the carriage, a fully formed flare would be created on one or more splines. Successive strokes of the carriage are performed after rotationally indexing the component to the next spline or set of splines, until the entire perimeter of the component is fully formed in this fashion.
The method of this invention thus provides an improved stator design and a method manufacturing a stator that provides a substantially improvement in the reliability, manufacturing costs and stator geometry as compared to known systems and methods.